An elevation of privilege vulnerability exists when the Windows Kernel API improperly handles registry objects in memory. An attacker who successfully exploited the vulnerability could gain elevated privileges on a targeted system. A locally authenticated attacker could exploit this vulnerability by running a specially crafted application. The security update addresses the vulnerability by helping to ensure that the Windows Kernel API properly handles objects in memory.
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1378